Radio Waves and Signals. Week 4. We imagine radio signals/waves travel as sine waves. The ripple of these waves are started by the vibration of an electron. The signal is produced in the circuits of the r adio, once the vibration leaves the radio through the antenna it becomes
travel as sine waves.
The ripple of these waves are started by
the vibration of an electron
circuits of the radio, once
the vibration leaves the
radio through the
a radio wave.
of the electromagnetic spectrum
of a vibrating
that carries the radio signal between the
mimic the signal that generated the wave.
This diagram actually shows 3 cycles.
travels in 1 complete cycle
is the frequency.
What is the
Frequency is measured in Hertz (Hz):
1 vibration/sec is 1 Hz
1330 KVOL broadcasts at 1,330,000 Hz
FM stations broadcasts in megahertz (MHz)
96.5 KPEL broadcasts at 96,500,000 Hz
What type of wave carries radio
signals between transmitting
and receiving stations?
What is the name for the distance
a radio wave travels during
1 complete cycle?
What term describes the number of times per second that an alternating current reverses direction.
A Hertz is ____ vibration(s) per _____ second(s)
What are the two components of a radio wave? (or any other wave in the electromagnetic
of light (c) through a particular type
The speed of light through
space is 300,000,000 m/s
Since all radio waves travel at the speed of light no matter what their frequency happens to be the following is true:
When length increases
then frequency decreases
when length decreases
then frequency increases.
wavelength or frequency because
the two are related by the speed of light.
it has a frequency of 150,000,000 Hz
300,000,000 / 150,000,000 = 2
This frequency typically would be referred to as 150 MHz
Wavelength in meters = 300 divided by frequency in megahertz.
To convert frequency to wavelength in meters divide 300 by frequency in MHz.
96.5 KPEL broadcasts at 96.5 MHz so the length of the waves is 300/96.5. The waves are approximately 3 meters in length.
The distance a wave travels during
1 complete cycle.
(Two acceptable ways to answer)
Speed of light
wavelength and frequency.
frequency into wave length (in meters)?
300 / Mhz
Approximate wavelengths are often used to identify the different frequency bands.
All types of radio frequency signals are referred to by the abbreviation RF, but for convenience the entire range is spilt into sub-ranges.
are generally “line of sight” communications.
That is they travel directly from the
transmitting station to the receiving
Normally used for local communication.
rarely heard from stations outside your
local coverage area because UHF signals
are not reflected by the ionosphere.
signals between two point are blocked by the
curvature of the Earth.
The radio horizon is somewhat farther than the
visual horizon because the earth seems less
curved to radio waves than light waves.
When using a hand-held transceiver inside a building you might want to choose to operate in a UHF band.
Knife-edge propagation is the term used to describe when signals are partially refracted around solid objectsexhibiting sharp edges.
of these frequency ranges?
3 – 30 MHz
30 – 300 MHZ
300 – 3000 MHz
limited to local communications?
UHF signals are not reflected
by the ionosphere.
radio signals are blocked by the curvature
of the Earth?
Why is the radio horizon somewhat farther that the visual line of sight distance between two stations?
The earth seems less curved
to radio waves than to
frequencies in the UHF band when using
a hand-held receiver inside a building?
The shorter waves length allows them to
more easily penetrate the structure of
signals are partially refracted (bent) around
solid objects with sharp edges?